The invention relates to a method for determining the filling capacity of tobacco, in which method, in a container closed on one side by a movable test plunger, a force is exerted on a given quantity of tobacco by the test plunger, and in which method the length of the tobacco column under the effect of the force and the time are measured.
The filling capacity corresponds to the visco-elasticity or compressibility of tobacco. It can be defined as the volume which a given mass of tobacco occupies after being subjected to a certain pressure for a certain time. The filling capacity of tobacco is greatly dependent on its temperature and moisture. As tobacco displays a marked relaxation behavior, a reproducible measurement of the filling capacity of tobacco is only possible using a process which is also precisely defined as regards time. The filling capacity depends on the type of tobacco and is an important characterizing variable for the evaluation of tobacco quality.
A method and an apparatus for the determination of the filling capacity of cut tobacco are known from the article, "Untersuchungen mit einem verbesserten Densimeter zum Pruefen der Fuell-faehigkeit von Schnittabak und der Haerte von Cigaretten", by H. W. Lorenz and F. Seehofer, Beitraege zur Tabakforschung, Volume 4, Issue 7 (1968). To measure the filling capacity, about 20 g of tobacco are poured loosely into a cylindrical container of about 60 mm diameter. After this container has been inserted in the known apparatus, a pressure plate on which a weight has been placed is lowered from above onto the tobacco by an electric motor. As soon as the pressure plate lies on the tobacco, the motor continues to run idle until it reaches an end position. The position of the pressure plate and consequently the height of the tobacco column is transmitted to a dial gauge or another display device. After a preselected time, of the order of one minute, has passed, the motor automatically lifts away the pressure plate with the superimposed weight from the compressed cut tobacco, and the final height of the tobacco column, which decreases with time, is displayed as a measure of the filling capacity.
In this method using the known apparatus, in the initial phase while the pressure plate is being lowered onto the cut tobacco the force acting on the tobacco builds up quickly but in a poorly reproducible manner. Thereafter the force is determined by the superimposed weight. The known method is consequently limited to the application of an essentially constant test force. Accurate measurement of a curve which represents the pattern of the final height of the tobacco column as a function of time is complicated because an individual measurement must be carried out for each time value. The temperature and the moisture or the water content of the tobacco, which have a considerable influence on the filling capacity, cannot be measured directly in the known apparatus. The moisture, for example, must be determined separately using a drying cabinet. The tobacco moisture can change during the lengthy filling capacity measurements or when the associated moisture determination is not carried out immediately before or after the measurements, which leads to a distortion of the results for the filling capacity.
The object of the invention is to provide a method of the type mentioned in the introduction for determining the filling capacity of tobacco which is not limited to the application of a constant test force. The filling capacity is to be measured with high accuracy taking into account the significant parameters. Moreover, the method is to be fully automatic. The method is to be usable for leaf tobacco as well as cut tobacco.
To achieve this object, the test plunger for exerting the force is driven by a motor in a pre-set manner, thereby compressing the tobacco, the force exerted on the tobacco is measured on the test plunger or on a supporting surface of the container, the length of the tobacco column is measured via the distance covered by the test plunger, the measured values for force and distance are acquired during the compression and sent via data transducers and interfaces to a computer for further processing, and further parameters governing the value of the filling capacity are determined in independent measurements and passed to a computer.
This means that the method runs reliably, quickly, easily and is user-friendly. Since the force acting on the tobacco is measured during the compression of the tobacco, a great many test possibilities open up for the evaluation of the variable "filling capacity" which is complex by nature. Driving the test plunger by a motor permits the use of larger containers to hold the tobacco, and as a result a larger quantity of tobacco can be tested and the reproducibility of the measured values obtained is improved. The use of larger containers to hold the tobacco also makes it possible to test leaf tobacco, so that the method is not restricted to cut tobacco. Filling capacity values obtained for leaf tobacco can be correlated with the filling capacity values for the cut tobacco obtained subsequently from the leaf tobacco, which produces specially reliable results, because both the leaf tobacco and the cut tobacco are tested according to the same method. Because the movement of the test plunger takes place in a pre-set manner, automatic calibration measurements for testing the unit can be integrated into the normal process procedure. All measured values are immediately sent to a computer, and thus an evaluation of the data, e.g. in the form of a curve showing the pattern of the force acting on the tobacco as a function of the length of the tobacco column, is considerably simplified. In addition, future changes in the test procedure can easily be made by modifications to the computer programs.
A further object of the invention is to determine the relaxation behavior of tobacco which is important for the evaluation of the filling capacity.
The object is achieved in that the test plunger rests in its end position for a relaxation period after the completion of its compression movement and in that the force acting on the tobacco is measured at predetermined time intervals during the relaxation period and transmitted to the computer for further processing.
In this way another informative curve is obtained which represents the force, decreasing in the course of the relaxation period, which the tobacco exerts on the test plunger, as a function of time. The conditions are well defined, because the length of the tobacco column is held constant. Altogether, therefore, curves are available with relevant data for the filling capacity, from which one or more values can be taken for the characterization of an assigned filling capacity value. Because the relaxation measurement takes place immediately following the compression movement of the test plunger, the total expenditure for the implementation of the method increases by only an insignificant amount as a result of the relaxation measurement.
Another object of the invention is to measure all the parameters governing the value of the filling capacity.
To achieve this object, during or immediately after the compression, the temperature and the moisture of the tobacco are determined by means of measurement devices fitted in the container or on the test plunger.
The fact that the measurements of the temperature and the moisture of the tobacco take place in the container and in immediate time proximity to the determination of the filling capacity data, ensures that their values also actually correspond to the temperature and moisture of the tobacco during the compression and relaxation measurements. Once these values are known, the filling capacity data of a given measurement or test procedure can be adjusted to reflect standard conditions (e.g. 22.degree. C., 12% tobacco moisture). This considerably simplifies the comparison of filling capacity data obtained in different measurements.
The invention also relates to a method for determining the hardness of cigarettes, in which method a force is exerted on a given number of cigarettes, lying on an essentially flat sample holder, by a test plunger which can be moved vertically to the surface of the sample holder and which has a pressure surface running parallel to the surface of the sample holder, and in which method the thickness of the cigarettes under the effect of the force and also the time are measured.
The hardness of a cigarette is a significant variable for the evaluation of its quality. The hardness is closely correlated with the filling capacity of the cut tobacco; a cut tobacco of high filling capacity produces a hard cigarette for a given cigarette size and a given tobacco weight. A method for determining the hardness of cigarettes can proceed in a completely analogous manner to a method for determining the filling capacity of tobacco. It is only necessary to ensure, by a suitable construction of the surfaces coming into contact with the tobacco product that the forces acting on the tobacco product are transmitted in a optimal manner.
Thus the already mentioned apparatus from the article "Untersuchungen mit einem verbesserten Densimeter zum Pruefen der Fuellfaehigkeit von Schnittabak und der Haerte von Cigaretten", by H. W. Lorenz and F. Seehofer, Beitraege zur Tabakforschung, Volume 4, Issue 7 (1968) also makes possible a method for determining the hardness of cigarettes. To carry out a hardness measurement, 10 cigarettes are placed on a base-plate which replaces the cylindrical container for cut tobacco. At the beginning of the hardness measurement the motor lowers onto the cigarettes from above a pressure plate matched in size to the base-plate, with a superimposed weight. The further procedure takes place exactly as described in connection with the determination of the filling capacity of cut tobacco. The disadvantages of the method implemented with the known apparatus are also for the determination of hardness limitation to an essentially constant test force, complicated and lengthy procedure, no simultaneous measurement of temperature and moisture of the cigarettes.
An apparatus for determining the hardness of cigarettes is also known in which, at the beginning of the hardness determination, a weight of ca. 5 g per cigarette is imposed on a given number of cigarettes by a motor via a pressure plate. At this moment the thickness of the cigarettes is measured, i.e. the distance between the base-plate beneath the cigarettes and the pressure plate. As the procedure continues the force on the cigarettes is increased, but is not measured until there is a defined value of ca. 250 g per cigarette. At this point, the thickness of the cigarettes is measured again. The method carried out with this known apparatus to determine the hardness of cigarettes thus supplies a link between the force and the thickness of the cigarettes, but there are only two measuring points for this. A fundamental problem in the use of weights is that the force acting on the tobacco product can be reduced by an unknown amount due to frictional forces.
It is an object of the invention to improve the method of the type mentioned before for determining the hardness of cigarettes. Like in the method for determining the filling capacity of tobacco, the method is not to be limited to a constant force acting on the cigarettes, or to only two different force values, it is to be fully automatic and is to supply measured data of a high degree of accuracy taking into account additional parameters governing the hardness.
This object is achieved in that the test plunger for exerting the force is driven in a pre-set manner by means of a motor, thereby compressing the cigarettes, the force exerted on the cigarettes is measured on the test plunger or on the sample holder, the thickness of the cigarettes is measured by means of the distance covered by the test plunger, the measured values for the force and distance are acquired during the compression and transmitted via data transducers and interfaces to a computer for further processing, and further parameters governing the value of the hardness are determined in independent measurements and passed to a computer.
In this way the advantages already mentioned in connection with the filling capacity determination of tobacco are achieved. Analogous to a large container for holding the cut tobacco or leaf tobacco, this time a large sample holder can be used on which many cigarettes can be placed. A good reproducibility of the measured force is then achieved, because during the course of the process an averaging takes place via a large number of cigarettes.
Another object of the invention, to obtain relevant relaxation data for the hardness of cigarettes, is achieved in that, after the completion of the compression movement of the test plunger, the test plunger rests in its end position for a relaxation period and that during the relaxation period the force acting on the cigarettes is measured at predetermined time intervals and transmitted to the computer for further processing. The thus obtained advantages correspond to those listed in connection with the relaxation measurements on tobacco.
The object of the invention to measure all parameters governing the value of the hardness of cigarettes is achieved in that the temperature and moisture of the cigarettes are determined during or immediately after compression by means of measurement devices fitted on the test plunger and/or on the sample holder. In this way reliable temperature and moisture values for the cigarettes are available which can be used for adjusting the hardness data obtained to reflect standard conditions (e.g. 22.degree. C., 12% moisture). This simplifies a comparison of hardness data which have been obtained in different measurement procedures.
The invention also relates to an apparatus for determining the filling capacity of tobacco, comprising a container, open on one side, for holding the tobacco, a test plunger, which can be moved in one direction into the container and which closes off the latter, for exerting a force on the tobacco, a distance-measurement device for determining the length of the tobacco column between the test plunger and a wall of the container lying opposite thereto, and a time-measurement device.
An apparatus of this generic type is known from the article, "Untersuchungen mit einem verbesserten Densimeter zum Pruefen der Fuellfaehigkeit von Schnittabak und der Haerte von Cigaretten", by H. W. Lorenz and F. Seehofer, Beitraege zur Tabakforschung, Volume 4, Issue 7 (1968) as discussed in connection with the method for determining the filling capacity of tobacco.
It is an object of the invention to provide an apparatus which implements the method for determining the filling capacity of tobacco as explained before.
To achieve this object, the apparatus comprises a computer-controlled drive device containing a motor for the test plunger for the exertion of the force on the tobacco, force-measurement devices fitted on the test plunger or on the supporting surface of the container, and data transducers and interfaces for the automatic acquisition of the measured values for the force and the length of the tobacco column and their transmission to a computer.
This apparatus has measurement devices fitted in the container or on the test plunger for the determination of the temperature of the tobacco and also data transducers and interfaces for the automatic acquisition of the values representing the temperature and their transmission to the computer. In an advantageous manner two platinum precision resistors for determining the temperature of the tobacco are fitted on the surface of the test plunger which is in contact with the tobacco and on the inner wall of the container which is opposite thereto.
The apparatus moreover has measurement devices fitted in the container or on the test plunger for determining the moisture of the tobacco and also data transducers and interfaces for the automatic acquisition of the values representing the moisture and for their transmission to the computer. In an advantageous manner, on the surface of the test plunger which is in contact with the tobacco and on the inner wall of the container which is opposite thereto in each case an arrangement composed of several mutually insulated electrodes is fitted which can be connected to a power source so as to determine by means of the measured current flowing through the tobacco and/or the measured voltage, the electrical conductivity as a measure of the moisture of the tobacco.
The drive device for the test plunger preferably contains a precision spindle rotated by a stepping motor, and the number of steps covered by the stepping motor is a measure of the length of the tobacco column.
The invention relates in addition to an apparatus for determining the hardness of cigarettes, comprising an essentially flat sample holder for holding the cigarettes, a test plunger movable vertical to the surface of the sample holder for exerting a force on the cigarettes, which has a pressure surface running parallel to the surface of the sample holder, a distance-measurement device for determining the thickness of the cigarettes situated between the pressure surface of the test plunger and the surface of the sample holder, and a time-measurement device.
An apparatus of this generic type is also known from the article, "Untersuchungen mit einem verbesserten Densimeter zum Pruefen der Fuellfaehigkeit von Schnittabak und der Haerte von Cigaretten", by H. W. Lorenz and F. Seehofer, Beitraege zur Tabakforschung, Volume 4, Issue 7 (1968) and has already been discussed in connection with the method for determining the hardness of cigarettes.
It is an object of the invention to provide an apparatus for determining the hardness of cigarettes which implements the method discussed above for determining the hardness of cigarettes.
The object is achieved in that the apparatus for determining the hardness of cigarettes comprises a computer-controlled drive device containing a motor, for the test plunger used to exert the force to the cigarettes, force-measurement devices fitted on the test plunger or on the sample holder, and data transducers and interfaces for the automatic acquisition of the measured values for the force and the thickness of the cigarettes and for their transmission to a computer.
Preferably, the apparatus for determining the hardness of cigarettes comprises measurement devices fitted on the sample holder, or on the test plunger, for determining the temperature and the moisture of the cigarettes, and also data transducers and interfaces for the automatic acquisition of the values representing the respective measured variable and for their transmission to the computer.
The drive device for the test plunger of this apparatus can have a precision spindle rotated by a stepping motor, in which the number of steps covered by the stepping motor can be used as a measure of the thickness of the cigarettes.
The test plunger is advantageously constructed in the shape of a ring. The sample holder for holding the cigarettes has a plurality of radially arranged recesses which are each about the length of a cigarette, formed plane in the central area opposite the test plunger and delimited, in the two end regions, from the respective neighboring recesses by ridges. With a thus constructed sample holder and the associated pressure surface, a large number of cigarettes can be subjected to the hardness determination simultaneously. The geometry of the pressure surface and the sample holder ensures that the forces can be transmitted evenly from the pressure surface of the test plunger to the cigarettes.
In order also to determine the firmness or hardness of the cigarette filters, the annular test plunger can preferably be removed from the apparatus and replaced by a second ring, which after fitting is situated above the region of the filters of the cigarettes lying in the sample holder. The test procedure for determining the hardness of the filters is identical to that for determining the hardness of the cigarettes.
It is also an object of the invention to provide an apparatus with which both the filling capacity of tobacco and also the hardness of cigarettes can be determined according to the methods explained above, so as to reduce the total costs of these machines.
This object is achieved in that, on a functioning apparatus for the determination of the filling capacity of tobacco, the test plunger for the filling capacity determination with the measurement devices situated thereon can be replaced by the test plunger for the hardness determination with the measurement devices situated thereon, and that the container for the filling capacity determination with the measurement devices situated therein can be replaced by the sample holder for the hardness determination with the measurement devices situated thereon.
These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.